An investigation to determine whether vitamin A, retinyl acetate, retinyl palmitate, or 13-cis-retinoic acid can retard or prevent the development of epidermoid carcinoma in two well defined oral mucous membrane tumor models - hamster buccal pouch and hamster tongue. Tumors are chemically induced by application of 9,10-dimethyl-1,2 benzanthracene (DMBA). Mineral oil is used as a vehicle for the buccal pouch applications and acetone for the tongue applications. Delayed tumor development will be evaluated grossly and microscopically. Radioactive retinoids and radioautography will be used to determine whether the retinoids localize in oral mucosa. Chemical studies will test for aryl hydrocarbon hydroxylase.